Réponses

2012-09-29T11:06:05+02:00

8x-x²(5x-1)

= - 5x^3 + x² + 8x

= -5x(x² - x/5 - 8/5)

 

x² - x/5 - 8/5

(x - 1/10)² = x² - x/5 + 1/100

 

donc x² - x/5 - 8/5 =

(x - 1/10)² - 161/100

= (x - 1/10 - (V161)/10)(x - 1/10 + (V161)/10)

= (x - (1+V161)/10)(x - (1- V161)/10)

 

8x-x²(5x-1)

= -5x(x-(1+V161)/10)(x-(1-V161)/10)

 

(3x-2)²-(2x-1)(3x-2)

= (3x-2)(3x-2-2x+1)

= (3x-2)(x-1)

 

En espérant t'avoir aidé.